Make the Crust

1. In a stand mixer, combine the diced butter, flour, salt, and cold water.
2. Mix until the dough is smooth and comes together.
3. Wrap the dough in plastic wrap and refrigerate for 1 hour.
4. Roll out the chilled dough to a thickness of ⅛ inch (3mm).
5. Cut out 2.5-inch (6 cm) circles using a cookie cutter or glass.
6. Place the Silpat® Mini Tartelette Mold on a perforated baking tray and press the dough rounds into the cavities.

Prepare the Filling

1. In a mixing bowl, whisk together the milk, cream, egg, nutmeg, and black pepper until smooth.

Prepare the Topping

1. In a pan over medium heat, sauté the bacon bits and chopped onions until golden and caramelized.
2. Drain the excess fat and set the mixture aside.

Assemble and Bake

1. Preheat the oven to 350°F (180°C).
2. Spoon the bacon and onion mixture into each prepared tartlet shell.
3. Pour the quiche filling into the shells, filling each just to the top of the filling ingredients.
4. Sprinkle shredded Gruyère cheese over the top.
5. Bake for 12-15 minutes, or until the tartlets are golden brown and set.
6. Let cool for a few minutes before serving.